1. Field of the Invention
The present invention relates to an absolute signal detecting method and an absolute encoder, and more particularly, to the new improvement for obtaining an absolute encoder in a structure almost similar to an incremental encoder.
2. Description of The Related Art
Heretofore, a commonly used absolute encoder, for example, one disclosed in Japanese Patent Laid-Open No. Hei 4-3 19621 uses one-track type of n-bit positional signals (well-known recurrent random number codes), detect said n-bit positional signals through disposing n pieces of light receiving elements corresponding to the n bits toward the track (toward the circumference), and output the n-bit positional signals as positional signals accompanying displacement of an input axis position of the encoder.
Since conventional encoders are composed as above described, there are following issues.
Thus, the necessary number of signal processing circuits corresponding to the n elements corresponding to said n bits is n series, problems such as signal adjustment of each of n series of circuits, and variance and frequency characteristics between n series occur, and hence, it is very difficult to produce absolute encoders in high reliability.
The present invention is to solve above issues, and in particular, an object of the present invention is to obtain an absolute signal detecting method and an absolute encoder in a structure almost similar to an incremental encoder.